Everyone wants his or her plants or garden to grow and be productive. Why else do you take the time and effort to plant and care for your plants? To achieve good results, plants need some essential nutrients. Unfortunately, most soils don’t provide the nutrients that plants require for optimal growth.
There are six macronutrients, in mineral form, that are required to produce plants: nitrogen, phosphorous, potassium, calcium, magnesium and sulfur. These nutrients are considered macronutrients because they are required in the greatest quantities. The first three nutrients – nitrogen, phosphorous and potassium – are commonly notated on plant fertilizers. Each of these nutrients has its own function in relation to cellular growth.
Nitrogen is necessary for plants to produce new tissues or leaf development. Lack of nitrogen can cause yellowing of the leaves and, because nitrogen is mobile inside a plant, the first signs of yellowing will occur in older leaves. Nitrogen is so necessary in new growth that the plant will rob the nitrogen from the older cells to grow new ones.
Phosphorous is the mineral that provides the energy to assist with the growth of roots and flowers. Stunted growth is a sign of phosphorus deficiency. When plants lack phosphorous, plant leaves can turn bluish-green since this mineral is needed for plants to utilize the sugars they produce. Too much sugar due to lack of energy will result in discolored leaves. Again, this symptom will appear in older leaves since phosphorous is a mobile mineral in a plant.
Potassium strengthens a plant by contributing to its early growth and regulating water movement in and out of a plant’s cell. Its presence is vital in the making of starch, which is used during the photosynthesis process. This mineral deficiency will show up in the older leaves, first as a dead spot. Plants low in potassium will often wilt because too much water leaves their cells.
Calcium aids in the growth of cell walls, and well-developed cell walls help plants resist disease. Calcium deficiency shows up first in the growing roots and young leaves with these plants parts showing malformation.
Magnesium has a key role in the photosynthesis process. A sign that magnesium deficiency is taking place is when then the leaves begin to lose their green color in between the leaf veins. The veins remain green, a condition that is known as interveinal chlorosis. The older leaves of the plant will reflect this deficiency first, which means that magnesium is mobile in plants.
Sulfur is a mineral that assists plants in growing, forming seeds and resisting diseases. Lack of sulfur will be reflected in the young leaves turning yellow. This is how you can tell a lack of sulfur from a nitrogen deficiency.
Determining what minerals your soil is lacking is the first step in producing a productive garden. An easy, low-cost soil test by your county extension agency will provide you the information to supplement your soil so that you can produce a bountiful garden. Once you get those test results you’ll be able to supplement your soil with the essential nutrients it may be lacking. Watch your plants for any noted problem or deficiency and you’ll be able to treat your plant with the proper mineral.
Mona Warlick, a Master Gardener, is a trained volunteer of the Mississippi State University Extension Service. For gardening questions, call the Help Center at (662) 620-8280 in Lee County or (866) 920-4678 outside Lee County and leave a message.